Welcome to ReefCentral.
Because of the sheer size of our forum, we've been forced to limit selling and trading to members who've met a couple of criteria. (If you're seeing this message, you haven't met them yet.) Please take a moment to acquaint yourself with our selling/trading rules to help make your stay a long and rewarding one.
Selling and trading on ReefCentral.

We had a tank full of asterina stars, so bought a harlequin shrimp. It ate a large sand sifting star, and has almost finished off the asterina stars. I keep seeing to get a chocolate chip starfish and cut off legs, and feed the shrimp that way. But I'd really rather have it eat the pests! If anyone knows where I can get asterina stars online, please let me know.

That's very interesting to hear that a population of asterinas can be wiped out by a harlequin shrimp. I would have thought that they reproduce faster. From your experience, can you estimate how big a population could be sustainable?

I don't know of anyone selling them. I do occasionally see them in tanks at my LFSs. You might try yours. Good luck!

__________________
As many naturalists and environmentalists have suggested, we should set aside our arrogance,
our desire to conquer and control everything, and walk hand in hand with Mother Nature. -Walter Adey

If you rely purely on asterina's your shrimp will eventually starve to death because there isn't enough food on each asterina to sustain them for the amount of time spent hunting. People have had them starve to death in tanks with plenty of asterina left to eat. You really need to be providing them larger stars.

If you rely purely on asterina's your shrimp will eventually starve to death because there isn't enough food on each asterina to sustain them for the amount of time spent hunting. People have had them starve to death in tanks with plenty of asterina left to eat. You really need to be providing them larger stars.

Yes this 100%... they don't eat the whole star... they only eat the feet. Asternia don't have enough meat to sustain them.
I hear if you keep more than 1 chocolate chip star (like 6 or something) and always rotate which one looses a leg, you'll never have to buy another star. But I am not a expert, in fact far from it. I've never owned a harlequin because I hate the idea of cutting legs off a live star. You can also cut a whole star up and keep it in the freezer feeding 1 leg at a time.

Some people have issues getting their harlequins to eat already dead/frozen stars also, so that needs to be kept in mind. They are definitely NOT a beginner or even medium level invert. Need to make sure you can afford to buy them a star a week or so.

They are awesome animals but the feeding requirements is what keeps me from getting any, and I love unique inverts far more than fish and coral, lol. I hate seeing people think they are just fancy pest control. I bet a huge number of them die because of that.

When I was big on harlequin shrimp, I had an asterina population in a separate 30 gallon where the glass was completely covered, intentionally as a backup supply during the winter months where shipping starfish and driving on frozen roads wasn't an option. That system started out with about 50 additions and then kinda ignored it for the next 6 months.

One week of a bad freeze, I would throw 30 in a day. Long story short, that system of stars stopped existing that same week, these shrimp need a lot of them... figure harlequin shrimp only eat the tube feet part of a starfish (which on paper isn't a lot of the animal), then scale the difference between a chocolate chip and an asterina, its impossible to sustain harlequins on purely asterinas. Really think about how many tube feet there are on the leg of a starfish, and you can assume 1 asterina = 1 tube foot, then account for all 5 legs.

Harlequins are either a full commitment to buying the starfish (or rotation method), or a rented service that goes back where it came from when the job is done. Unless you have the literal ocean's worth of asterinas being given to you, its best to work with 1 medium chocolate chip star to last for 2 weeks, or 1 small for about a week, depending how fast or slow it dies, both in cost and results.

Sorry I've not logged on lately, and see some great responses. I haven't seem the harlequin in about two weeks now, and fear I starved it to death, which makes me really sad because I didn't realize that when the asterina population shrunk, it would take so much more effort to get food. I've also read that trigger fish may kill harleys, true? We have a gorgeous blue trigger that just may have to go back to the store. It killed a goby and if it also killed the harley, I will want to take it out of our otherwise peaceful tank.